Method of forming ferroelastic lead germanate thin films

ABSTRACT

A Pb 3 GeO 5  phase PGO thin film is provided. This film has ferroelastic properties that make it ideal for many microelectromechanical applications or as decoupling capacitors in high speed multichip modules. This PGO film is uniquely formed in a MOCVD process that permits a thin film, less than 1 mm, of material to be deposited. The process mixes Pd and germanium in a solvent. The solution is heated to form a precursor vapor which is decomposed. The method provides deposition temperatures and pressures. The as-deposited film is also annealed to enhanced the film&#39;s ferroelastic characteristics. A ferroelastic capacitor made from the present invention PGO film is also provided.

CROSS REFERENCE TO RELATED APPLICATIONS

[0001] This application is a divisional of application Ser. No.09/301,434 filed Apr. 28, 1999, entitled “Ferroelastic Lead GermanateThin Film and Deposition Method,” invented by Tingkai Li et al.

BACKGROUND AND SUMMARY OF THE INVENTION

[0002] The present invention relates generally to the field ofintegrated circuit (IC) fabrication and, more particularly, to aferroelastic lead germanate film and metal organic chemical vapordeposition (MOCVD) method for the above-mentioned thin film.

[0003] Ferroelastic films have attracted great interest in recent yearsbecause of their potential for use in applications such as high-energystorage capacitors and high-strain actuators/transducers. More recently,with the development of microelectronic devices, ferroelastic thin filmshave been explored for use in microactuators, microelectromechanicalsystems (MEMS), and as decoupling capacitors in high speed multichipmodules (MCMs). It has been found that for charge storage applications,ferroelastics are superior to ferroelectrics because the stored chargecan be completely released due to absence of remanent polarization.Ferroelastic films are superior to films with linear dielectrics becauseof their high dielectric constant and high charge storage density.However, it is difficult to obtain ferroelastic thin films with squarehysteresis loops and zero remanent polarization.

[0004] The fabrication and characterization of ferroelastic leadgermanium oxide thin films (PGO), especially Pb₃GeO5 are of currentinterest. Lead germanate is a relative new materials. The PbO—GeO2binary system has been studied by Speranskaya (1959). R. R. Neurgaonkaret al. grew single crystal of ferroelastic Pb₃GeO₅ by the Czochralskitechnique (1974). The ferroelastic properties in this material werefirst discovered by R. R. Neurgaonkar et al. The dielectric andelectric-optics properties of single crystal and polycrystallinematerials have been reported in the literature. The ferroelastic Pb₃GeO5belongs to the monoclinic space group P2 at room temperature. Thecrystals are ferroelastic, but show no phase transitions up to themelting point (738° C.). The interesting feature of this material isthat Pb₃GeO₅ has ferroelastic properties, which are suitable formicroelectromechanical system (MEMS) applications.

[0005] Ferroelectric lead germanate (Pb₅Ge₃O₁₁) thin films have beenmade by thermal evaporation and flash evaporation (A. Mansingh et al.,1980), dc reactive sputtering (H. Schmitt et al., 1984), laser ablation(S. B. Krupanidhi et al., 1991 and C. J. Peng et al., 1992), and sol-geltechnique (J. J. Lee et al., 1992). However, ferroelastic Pb₃GeO₅ thinfilms made by MOCVD processes have not been reported.

[0006] The present invention PGO film has ferroelastic properties thatare useful in microelectromechanical system (MEMS) and high speedmultichip module (MCM) applications. In co-pending patent applicationSer. No. 09/301,435, entitled “Multi-Phase Lead Germanate Film andDeposition Method”, invented by Tingkai Li et al., filed on Apr. 28,1999, attorney docket No. SLA400, a second phase of Pb₃GeO₅ is added tothe Pb₅Ge₃O₁₁, increasing grain sizes without an increase in c-axisorientation. The resultant film has increased Pr values and dielectricconstants, and decreased Ec values. Such a film is useful in MEM, MCM,DRAM, and FeRAM applications.

[0007] In co-pending patent application Ser. No. 09/301,420, entitled“C-Axis Oriented Lead Germanate Film and Deposition Method for Same”,invented by Tingkai Li et al., filed on Apr. 28, 1999, attorney docketNo. SLA401, the Pb₅Ge₃O₁₁, film is crystallographically oriented in thec-axis. This film has smaller Pr and dielectric constant values, and isuseful in one transistor (1T) applications.

[0008] In co-pending patent application Ser. No. 09/302,272, entitled“Epitaxially Grown Lead Germanate Film and Deposition Method”, inventedby Tingkai Li et al., filed on Apr. 28, 1999, attorney docket No.SLA402, now U.S. Pat. No. 6,190,925, an epitaxial grown PGO film isdisclosed with extremely high c-axis orientation. As a result, high Prand Ec values, as well as lower dielectric constant, is obtained. Such afilm is useful in 1T, and one transistor/one capacitor (1T/1C.) FeRAMapplications. The three above-mentioned co-pending patent applicationsare incorporated herein by reference.

[0009] It would be advantageous if a CVD process could be developed forthe deposition of ferroelastic PGO thin films.

[0010] It would be advantageous if a CVD process, offering theadvantages of excellent film uniformity, compositional control, highfilm densities, high deposition rates, excellent step coverage, andcommercial amenability, could be developed for PGO processes.

[0011] Accordingly, a method for forming a ferroelastic lead germaniumoxide (PGO) film on an integrated circuit (IC) IC wafer has beenprovided. Typically, the wafer is at least partially covered with aconductive electrode material of Ir or Pt. The method comprises thesteps of:

[0012] a) mixing [Pb(thd)₂] and [Ge(ETO)₄] to form a PGO mixture havinga molar ratio of about 3:1;

[0013] b) dissolving the mixture of Step a) with a solvent oftetrahydrofuran, isopropanol, and tetraglyme, having a molar ratio ofabout 8:2:1, respectively, to form a precursor solution having aconcentration of approximately 0.1 to 0.5 moles of PGO mixture per literof solvent;

[0014] c) introducing the precursor solution to a precursor vaporizer ata rate in the range of approximately 0.1 to 0.5 milliliters per minute(ml/min), and heating the solution to create a precursor gas having atemperature in the range of approximately 180 to 250 degrees C. and aprecursor vapor pressure in the range of approximately 30 to 50 torr(T);

[0015] c₁) mixing the precursor gas in the chamber with an argon gasshroud flow in the range of approximately 4000 to 6000 square cubiccentimeters per minute (sccm), preheated to a temperature in the rangeof approximately 170 to 250 degrees C.;

[0016] c₂) introducing an oxygen flow to the reactor in the range ofapproximately 1000 to 3000 sccm, whereby a lead-germanium oxide with ac-axis orientation is promoted;

[0017] d) heating the wafer chuck to a temperature in the range ofapproximately 500 to 650 degrees C., establishing a reactor chamberpressure in the range of approximately 5 to 10 T, and decomposing theprecursor gas on the IC wafer to form a PGO thin film with a thicknessof less than 1 millimeter (mm), including a first phase of Pb₃GeO₅,whereby the PGO film having ferroelastic properties is formed;

[0018] e) cooling the PGO film to approximately room temperature in anoxygen atmosphere; and

[0019] f) annealing the PGO film formed in Step d) in an atmosphereselected from the group of oxygen and oxygen with Pb atmospheres, withthe oxygen being introduced at a partial pressure greater thanapproximately 20%, whereby the ferroelastic properties of the PGO filmare improved.

[0020] In some aspects of the invention further steps follow Step f) of:

[0021] g) forming a conductive electrode overlying the PGO film; and

[0022] h) annealing the PGO film in an atmosphere selected from thegroup of oxygen and oxygen with Pb atmospheres, with the oxygen beingintroduced at a partial pressure greater than approximately 20%, wherebythe interface between the PGO film and the electrode formed in Step g),is improved.

[0023] Typically, Steps f) and h) include using a rapid thermalannealing (RTA) process to anneal the PGO film, in which thetemperatures are in the range of approximately 500 to 750 degrees C.,for a duration in the range of approximately 10 to 30 minutes, and athermal temperature ramp-up in the range of approximately 10 to 200degrees C. per second. Alternately, furnace annealing is performed attemperatures between 500 and 600 degrees for time durations of 30minutes to 2 hours.

[0024] A lead germanium oxide (PGO) thin film having ferroelasticproperties is also provided. The PGO film comprises a first phase ofPb₃GeO₅, with the thickness of the first phase of Pb₃GeO₅ being lessthan approximately 1 mm, whereby said Pb₃GeO₅ phase improves theferroelastic properties of the PGO film. Typically, the first phasePb₃GeO₅ has a grain size in the range of approximately 1 to 2 microns.

[0025] Also provided is a capacitor. The capacitor comprises a firstconductive electrode, a PGO thin film including a first phase of Pb₃GeO₅overlying the first electrode, and a second conductive electrodeoverlying the PGO film, whereby a PGO film capacitor is formed havingferroelastic properties. The capacitor has a dielectric constant in therange of approximately 50 to 100, and a leakage current of 4×10⁻⁶ A/cm2at 100 kV/cm. The minimum polarization voltage is approximately 1 volt,and the saturation voltage is less than approximately 5 volts.

BRIEF DESCRIPTION OF THE DRAWINGS

[0026]FIG. 1 illustrates steps in a method for forming a ferroelasticlead germanium oxide (PGO) film.

[0027]FIG. 2 illustrates a completed present invention capacitor.

[0028]FIG. 3 is the X-ray pattern of Pb5Ge₃O₁₁ films of the presentinvention deposited at 550° C.

[0029]FIG. 4 is a SEM micrograph of the present invention PGO film.

[0030]FIG. 5 illustrates maximum polarization (Pm) and switching fields(Es) of the present invention films.

[0031]FIG. 6 illustrates an I-V curves of the present invention PGOfilm.

[0032]FIG. 7 illustrates the dielectric constant of the presentinvention PGO films.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

[0033] The ferroelastic Pb₃GeO₅ thin films were prepared on Ir or Ptcoated Si wafers by metalorganic vapor deposition (MOCVD) and RTP (RapidThermal Process) annealing techniques. The films were specular and crackfree and showed completely crystallization between 500 and 650° C. Goodferroelastic properties were obtained for a 300 nm thick film with Ir orPt electrodes. Polarization can be generated at an applied voltage aslow as 1V, and almost complete saturation occurs at 5V. Polarizationdisappears after removal of the applied voltage. The leakage currentsincreased with increasing applied voltage, and were found about 4×10⁻⁶A/cm² at 100 kV/cm. The dielectric constant showed the similar behaviorto the most ferroelastic materials, which dielectric constant changingwith respect to the applied voltage. The maximum dielectric constant wasabout 50-100. This high quality MOCVD Pb₃GeO₅ films can be used forapplications of microelectromechanical system (MEMS) and decouplingcapacitors in high speed multichip modules (MCMs).

[0034] The lead germanium oxide (PGO) thin film of the present inventionhas ferroelastic properties. These films comprise a first phase ofPb₃GeO₅. The thickness of said first phase of Pb₃GeO₅ is less thanapproximately 1 mm, whereby said Pb₃GeO₅ phase improves the ferroelasticproperties of the PGO film. Typically, the first phase Pb₃GeO₅ has agrain size in the range of approximately 1 to 2 microns.

[0035] An EMCORE oxide, or other similar MOCVD reactor with liquiddelivery system was used for the growth of Pb3GeO5 films. Such a systemis shown in FIG. 1 of co-pending patent application Ser. No. 09/301,435,entitled “Multi-Phase Lead Germanate Film and Deposition Method”,invented by Tingkai Li et al. The Pb₃GeO₅ films were deposited on 6″ Ptor Ir covered Si wafers using MOCVD processes. The precursors for PGOthin films listed in Table 1. TABLE 1 The properties of precursors forPGO thin films Vapor Pressure Decomposition Precursors Formula (mm Hg)Temperature (° C.) Pb(Ttd)₂ Pb(C₁₁H₁₉O₂)₂ 180° C./0.05 325° C. Ge(ETO)₄Ge(C₂H₅O)₄ b.p. 185.5° C.

[0036] [Pb(thd)₂] and [Ge(ETO)₄] in a molar ratio of 3:1 were dissolvedin a mixed solvent of butyl ether (or tetrahydrofuran), isopropanol, andtetraglyme in the molar ratio of 8:2:1. The precursor solutions have aconcentration of 0.1-0.5 M/L of Pb₃GeO₅. The solution was injected intoa vaporizer (180-250° C.) by a pump at a rate of 0.1-0.5 ml/min to formprecursor gases. The precursor gases were brought into the reactor usinga preheated argon flow at 170-250° C. The deposition temperatures andpressure are 500-650° C. and 5-10 Torr, respectively. The shroud flow(Ar 4000-6000 sccm) with oxygen (1000-3000 sccm) was led into thereactor. After deposition, the Pb₃GeO₅ films were cooled down to roomtemperature in an oxygen atmosphere. The Pb₃GeO₅ films werepost-annealed before, and after, deposition of the top electrodes usingRTP method. The post-annealing step before deposition of top electrodesis defined herein as the first annealing, and the post-annealing afterdeposition of top electrodes is defined as the second annealing.

[0037] The basic composition, phase, and electrical properties of thesome early experimental Pb₃GeO₅ films have been measured. Thecompositions of the Pb₃GeO₅ films were analyzed by using energydispersion X-ray analysis (EDX). The phases of the films were identifiedusing X-ray diffraction. The thickness and surface morphologies of thefilms on Ir/Ti/SiO₂/Si substrates were investigated by ScanningElectronic Microscope (SEM). The leakage currents and dielectricconstants of the films were measured using HP4155-6 precisionsemiconductor parameter analyzer and Keithley 182 CV analyzerrespectively. Other properties of the films were measured by astandardized RT66A tester.

[0038] The present invention PGO films were deposited at temperatureabout 500-650° C. The as-deposited films were specular, crack-free, andadhered well to the substrates. These films also showed very smoothsurfaces as viewed by means of both optical microscopy and scanningelectron microscopy. The film growth rates were typically in the rangeof 2-5 nm/min.

[0039]FIG. 1 illustrates steps in a method for forming a ferroelasticlead germanium oxide (PGO) film. Step 100 provides an integrated circuit(IC) wafer or film. Typically, a further step (not shown), precedes Step102, of depositing a conductive electrode overlying the IC wafer. Theconductive electrode material is selected from the group consisting ofIr and Pt. Step 102 mixes [Pb(thd)₂] and [Ge(ETO)₄] to form a PGOmixture having a molar ratio in the range of approximately 2:1 to 4:1.Typically, the molar ratio is approximately 3:1, but the ratio isaltered in response to the temperature of the precursor vapor and thepresence of a partial Pb atmosphere in the reactor chamber.

[0040] Step 104 dissolves the mixture of Step 102 with a solvent oftetrahydrofuran, isopropanol, and tetraglyme to form a precursorsolution. In some aspects of the invention, Step 104 includes thesolvents tetrahydrofuran, isopropanol, and tetraglyme being in a molarratio of approximately 8:2:1, respectively. Typically, Steps 102 and 104are performed simultaneously, and Step 104 includes forming a precursorsolution having a concentration of approximately 0.1 to 0.5 moles of PGOmixture per liter of solvent. Tables 2 and 3 display precursor andsolvents that are alternately used with the present invention process.TABLE 2 The properties of precursors for PGO films Appearance at Vaporroom Moisture Pressure Decomposition Precursor Formula temperaturestability (mm Hg) Temp. (° C.) GeH₄ Ge₂H₆ Ge₃H₅ Ge(ETO)₄ Ge(OC₂H₅)₄colorless sensitive 185° C. liquid GeCl₄ (C₂H₅)₂GeCl₂ Pb Pb(C6H5)4 white230° C./0.05 325° C. Tetraphenyl powder Pb(TMHD)₂ Pb(C₁₁H₁₉O₂)₂ white180° C./0.05 325° C. powder Pb(C₂H₅)₄

[0041] TABLE 3 The properties of solvents for PGO films Solvents FormulaBoiling Temp. (° C.) Tetrahydrofuran C₄H₈O 65-67° C. (THF) Iso-propanolC₃H₇OH 97° C. Tetraglyme C₁₀H₂₂O₅ 275° C. Xylene C₆H₄(CH₃)₂ 137-144° C.Toluene C₆H₅CH₃ 111° C. Butyl ether [CH₃(CH₂)₃]₂O 142-143° C. Butylacetate CH₃CO₂(CH₂)₃CH₃ 124-126° C. 2-Ethyl-1-hexanolCH₃(CH₂)₃CH(C₂H₆)CH₂ 183-186° C. OH

[0042] Step 106 heats the solution formed in Step 104 to create aprecursor gas. Typically, Step 100 provides a precursor vaporizerauxiliary to the reactor, and Step 106 includes using the precursorvaporizer to heat the precursor solution to a temperature in the rangeof approximately 180 to 250 degrees C., whereby the precursor gas isformed. In some aspects of the invention, Step 100 provides a liquidpump. Then a further step is performed, following Step 104, andpreceding Step 106. Step 104 a (not shown) uses the liquid pump tointroduce the precursor solution of Step 104 to the precursor vaporizerin Step 106 at a rate in the range of approximately 0.1 to 0.5milliliters per minute (ml/min).

[0043] Step 108 decomposes the precursor gas formed in Step 106 on theIC wafer to form a PGO thin film, including a first phase of Pb₃GeO₅.Unlike a bulk material, Step 108 typically includes forming a PGO filmhaving a film thickness of less than approximately 1 millimeter (mm).Step 110 is a product where the PGO film that is formed has ferroelasticproperties.

[0044] In some aspects of the invention, Step 100 provides that the ICwafer is located in a reactor chamber or vacuum chamber. Alternately,the IC wafer is introduced in a step (not shown) before Step 108.Regardless, Step 106 a mixes the precursor gas in the chamber with anargon gas shroud flow in the range of approximately 4000 to 6000 squarecubic centimeters per minute (sccm), preheated to a temperature in therange of approximately 170 to 250 degrees C. Then, Step 106 b introducesan oxygen flow to the reactor in the range of approximately 1000 to 3000sccm.

[0045] Further, Step 100 provides that the IC wafer is located on awafer chuck in the reactor with a chamber pressure established topromote the flow of precursor and gases. Step 106 includes establishinga precursor vapor pressure in the range of approximately 30 to 50 torr(T). Step 108 includes heating the wafer chuck to a temperature in therange of approximately 500 to 650 degrees C. and establishing a reactorchamber pressure in the range of approximately 5 to 10 T. Alternatelysaid, the oxygen partial pressure is greater than 10%, preferably in therange of approximately 20 to 50%.

[0046] Typically, a further step follows Step 108. Step 108 a cools thePGO film to approximately room temperature in an oxygen atmosphere. Step112 anneals the PGO film formed in Step 108 in an atmosphere selectedfrom the group of oxygen and oxygen with Pb atmospheres, whereby theferroelastic properties of the PGO film are improved. Typically the Pbatmosphere is in the range of approximately 0 to 30%.

[0047] In some aspects of the invention a ferroelastic device is formedwith the PGO film of in Step 108. Then, further steps follow Step 112.Step 114 forms a conductive electrode overlying the PGO film. Step 116anneals the PGO film in an atmosphere selected from the group of oxygenand oxygen with Pb atmosphere. The interface between the PGO film,formed in Step 108, and the electrode formed in Step 114, is improved.Typically, Steps 112 and 116 include the oxygen being introduced at apartial pressure greater than approximately 20%.

[0048] Steps 112 and 116 include using annealing methods selected fromthe group consisting of furnace annealing at a temperature in the rangeof approximately 500 to 600 degrees C. for a duration of approximately30 minutes to 2 hours, and rapid thermal annealing using temperatures inthe range of approximately 500 to 750 degrees C. When RTA is used inSteps 112 and 116, the duration is in the range of approximately 10 to1800 seconds, and the thermal temperature ramp-up in the range ofapproximately 10 to 200 degrees C. per second. In some aspects of theinvention, the first annealing step is a furnace anneal, and the secondanneal is an RTA anneal. Steps 108, 112, and 118 include the Pb₃GeO₅first phase having a grain size in the range of approximately 1 to 2microns.

[0049]FIG. 2 illustrates a completed present invention capacitor havingferroelastic properties. Capacitor 200 comprises a first conductiveelectrode 202, a PGO thin film 204 including a first phase of Pb₃GeO₅overlying first electrode 202, and a second conductive electrode 206overlying PGO film 204, whereby a PGO film capacitor is formed havingferroelastic properties.

[0050] Capacitor 200 has ferroelastic properties include a dielectricconstant in the range of approximately 50 to 100, and a leakage currentof 4×10⁻⁶ A/cm2 at 100 kV/cm. The minimum polarization voltage isapproximately 1 volt and the saturation voltage is approximately 5volts.

[0051]FIG. 3 is the X-ray pattern of Pb₃GeO₅ films of the presentinvention deposited at 550° C. The composition and X-ray analysisconfirm the formation of polycrystalline Pb₃GeO₅ films.

[0052]FIG. 4 is a SEM micrograph of the present invention PGO film. Theaverage grain size of the films is about 1.5 μm. The thickness ismeasured about 300 nm. For the surface morphology, the film appears tohave uniformly distributed fine grains, appears to be crack-free underSEM examinations.

[0053]FIG. 5 illustrates maximum polarization (Pm) and switching fields(Es) of the present invention films. The as-deposited Pb₃GeO₅ films showgood ferroelastic properties. After the RTP annealing at 550-600° C. for0.5 hour, the Pb₃GeO₅ films exhibited a symmetrical ferroelastichysteresis loop with higher polarization (Pm) and lower switching field(Es). Polarization disappears after removal of the switching field, asshown in FIG. 5. Polarization appears even at very low switching voltageof 1V, and increases as the switching voltage increases.

[0054]FIG. 6 illustrates an I-V curves of the present invention PGOfilm. Low leakage current density is an important consideration formicroelectromechanical device applications. FIG. 6 shows the I-V curveof 300 nm thick MOCVD PGO films. Excellent I-V characteristics areobserved. The leakage current density of the Pb₃GeO₅ thin filmsincreases as the applied voltage is increased, and is about 4×10⁻⁶ A/cm²at 100 KV/cm.

[0055]FIG. 7 illustrates the dielectric constant of the presentinvention PGO films. The dielectric constant is also another importantissue for microelectromechanical system (MEMS) and decoupling capacitorsin high speed multichip modules (MCMs). The dielectric constant of thePb₃GeO₅ thin films show behavior similar to the most ferroelasticmaterials, where the dielectric constant changes with applied voltage.The maximum dielectric constant of the Pb₃GeO₅ thin films is about50-100. Note, FIGS. 3-7 illustrate the results of experimental films,and are not necessarily optimum values.

[0056] A Pb₃GeO₅ phase PGO thin film is provided. This film hasferroelastic properties that make it ideal for manymicroelectromechanical memory cell applications. This PGO film isuniquely formed in a MOCVD process that permits a thin film, less than 1mm, of material to be deposited. A ferroelastic capacitor and MOCVDdeposition method for this PGO film are also provided. Other embodimentsand variations of the present invention will occur to those skilled inthe art.

What is claimed is:
 1. A method for forming a ferroelastic leadgermanium oxide (PGO) film on an integrated circuit (IC) wafercomprising the steps of: a) mixing [Pb(thd)₂] and [Ge(ETO)₄] to form aPGO mixture having a molar ratio in the range of approximately 2:1 to4:1; b) dissolving the mixture of Step a) with a solvent oftetrahydrofuran, isopropanol, and tetraglyme to form a precursorsolution; c) heating the solution formed in Step b) to create aprecursor gas; and d) decomposing the precursor gas formed in Step c) onthe IC wafer to form a PGO thin film, including a first phase ofPb₃GeO₅, whereby the PGO film having ferroelastic properties is formed.2. A method as in claim 1 in which Step a) includes mixing the[Pb(thd)₂] and [Ge(ETO)₄] in a molar ratio of approximately 3:1.
 3. Amethod as in claim 1 in which Step b) includes the solventstetrahydrofuran, isopropanol, and tetraglyme being in a molar ratio ofapproximately 8:2:1, respectively.
 4. A method as in claim 1 in whichStep b) includes forming a precursor solution having a concentration ofapproximately 0.1 to 0.5 moles of PGO mixture per liter of solvent.
 5. Amethod as in claim 1 wherein a liquid pump and precursor vaporizer areprovided, in which Step c) includes using the precursor vaporizer toheat the precursor solution to a temperature in the range ofapproximately 180 to 250 degrees C., whereby the precursor gas isformed, and including a further step, following Step b), and precedingStep c), of: b₁) using the liquid pump to introduce the precursorsolution of Step b) to the precursor vaporizer in Step c) at a rate inthe range of approximately 0.1 to 0.5 milliliters per minute (ml/min).6. A method as in claim 1 in wherein the IC wafer is located in areactor, and a further steps of: c₁) mixing the precursor gas in thechamber with an argon gas shroud flow in the range of approximately 4000to 6000 square cubic centimeters per minute (sccm), preheated to atemperature in the range of approximately 170 to 250 degrees C.; and c₂)introducing an oxygen flow to the reactor in the range of approximately1000 to 3000 sccm.
 7. A method as in claim 1 wherein the IC wafer islocated on a wafer chuck in a reactor, in which Step c) includesestablishing a precursor vapor pressure in the range of approximately 30to 50 torr (T), and in which Step d) includes heating the wafer chuck toa temperature in the range of approximately 500 to 650 degrees C. andestablishing a reactor chamber pressure in the range of approximately 5to 10 T.
 8. A method as in claim 1 including further steps followingStep d) of: e) cooling the PGO film to approximately room temperature inan oxygen atmosphere; and annealing the PGO film formed in Step d) in anatmosphere selected from the group of oxygen and oxygen with Pbatmospheres, whereby the ferroelastic properties of the PGO film areimproved.
 9. A method as in claim 8 wherein a ferroelastic device isformed with the PGO film of in Step d), and including further stepsfollowing Step f) of: g) forming a conductive electrode overlying thePGO film; and h) annealing the PGO film in an atmosphere selected fromthe group of oxygen and oxygen with Pb atmospheres, whereby theinterface between the PGO film, formed in Step d), and the electrodeformed in Step g), is improved.
 10. A method as in claim 9 in whichSteps f) and h) include the oxygen being introduced at a partialpressure greater than approximately 20%.
 11. A method as in claim 9 inwhich Steps f) and h) include using annealing methods selected from thegroup consisting of furnace annealing at a temperature in the range ofapproximately 500 to 600 degrees C. for a duration of approximately 30minutes to 2 hours, and rapid thermal annealing (RTA) at a temperaturesin the range of approximately 500 to 750 degrees C.
 12. A method as inclaim 9 in which Steps f) and h) in which the RTA includes a duration inthe range of approximately 10 to 1800 seconds, and a thermal temperatureramp-up in the range of approximately 10 to 200 degrees C. per second.13. A method as in claim 9 in which Steps d), f), and h) include thePb₃GeO₅ first phase having a grain size in the range of approximately 1to 2 microns.
 14. A method as in claim 1 including a further step,preceding Step a), of: depositing a conductive electrode overlying theIC wafer, the conductive electrode being selected from the groupconsisting of Ir and Pt.
 15. A method as in claim 1 in which Step d)includes forming a PGO film having a film thickness of less thanapproximately 1 millimeter (mm).